The World's Fastest B Motor Slot Car
Part 1 - The Motor
By Rick Thigpen
The title of this article, "The Worlds Fastest B-motor Slot Car", is the goal, not a statement of fact. It might actually be attainable if no one else is crazy enough to mess around with the infamous Mura B-can! Well I never said I wasn’t crazy, so I’m going to give it a try.
I’m starting with a B-motor build up inspired by a "how to" article in Model Racing Journal May 7, 1970. But first a little background. Here is the first ad for Mura’s 1969 B-Production motor:
Here is an original motor:
John Cukras was working for Mura at the time and lead the B-motor charge into the Pro Racing ranks in 1969. The motor wasn’t performing up to expectations so the first round of modifications resulted in this version with a large rectangular cutout replacing the 2 cooling holes in the can. This is a motor built by DART:
Still not satisfied with the new motors performance another round of changes ensued. This time the .042" thick can was milled on the top and bottom to a thickness of .020", the 2 cooling holes made a comeback, brush cooling cut outs were added and the can was notched for axle clearance. Here is the old dog I’m starting with for my build:
There was one more important difference. The inside of the can was "circular milled" for more armature clearance. The thinking was that the motor was so low profile there wasn’t enough air gap between the armature and the top and bottom of the can. Here is a close up of the "circular milling".
Here is a still later version this time in NCC20 form. The can is now made of .030" thick material and the rectangular cutouts return:
All four of the can versions lined up with the oldest at the rear:
Time for the MRJ "how to" article:
